(1) Field of the invention
This invention relates to a bottle cap wholly made of a synthetic plastic material. More particularly, it relates to a bottle cap comprised of an inner stopper member made of a flexible plastic material and an outer cap member made of a plastic material more rigid than that of the inner stopper member.
(2) Description of the Prior Art
Many tamper-indicating bottle caps have been used for packaging beverages and other liquids. Typical tamper-indicating bottle caps are metal twist-off caps having a severable metal ring which fractures upon twisting the caps so as to remain on the bottle neck as a tamper-indicating band when the cap has been removed. These types of caps result in a sharp edge remaining on the cap portion which has been removed and on the tamper-indicating band which remains on the container. These sharp edges are inherently dangerous to the consumer utilizing the packages. In addition, twist-off caps require more expensive and complicated application machinery than does a simple push-on closure.
U.S. Pat No. 3,976,215 discloses a tamper-indicating press-on, pull-off cap providing a package which may be readily opened by a consumer without the use of tools and without the creation of dangerous sharp edges. This press-on, pull-off cap is comprised of an outer metal cap member and an inner plastic cap member which fits within the outer metal cap member and which is formed integrally with a pull ring for removal of the cap from the bottle.
Conventional tamper-indicating caps comprised of independent inner and outer cap members, which include the above-mentioned press-on, pull-off cap, have a disadvantage. That is, the inner and outer cap members must be shipped and stored in a separated form and must be combined when the inner and outer cap members are brought into sealing engagement with the bottle neck in the step of stoppering the bottle. Therefore, the step of stoppering the bottle requires complicated application machinery.
Some conventional tamper-indicating caps comprised of inner and outer cap members have a structure such that the inner and outer cap members can be shipped and stored in a combined form so as to be readily pressed into sealing engagement with the bottle neck in the step of stoppering the bottle. However, these caps have the disadvantage that the outer cap member combined with the inner cap member is inadvertently brought into a seal position relative to the inner cap member during shipping and storage.